Antenna array



s m N m S u B G H.

July 6, E4.

Y m A N N E T N A 8 Sheets-Sheet 1 Filed Aug. 9, 1943 PHASE C'MOLRiff/VER TIM/Fu lof/H3 E CONT/ml (2@ INVENToR. Hf/VF/ G. 50S/@NMS BYTTRVEY Juy 65, g4, H, G, BUSIGNlEs 2,444,425

ANTENNA ARRAY Filed Aug. 9, 1943 8 Sheets-Sheet 2 ,71.2 awe@ oF H6, I.

IN VEN TOR. IIE/WPI 6. 805/611056 A TTHNEY MY @y 1948. H. G. EUSIGNIES2,444,425

4ANTENNA ARRAY IN VEN TOR. r "7-` HfA//P/ G. 50s/GMES /1 TTOHNE' 8Sheets-Sheet 4.

ANTENNA ARRAY H. G. BUSIGNIES Filed Aug. 9. 194s I N V EN TOR. HENR/ G.BUS/GMES ATT//VEY July 1948. H. G. auslGNlEs ANTENNA ARRAY INVENTOR.Hfwe/ G. aas/@Mes :216

my 6 1948 H. G. BuslGNlEs ANTENNA ARRAY 8 Sheets-Sheet 6 Filed Aug.' 9,1943 MY 6, 1948. H. G. BuslGNlEs 2,444,425

ANTENNA Amr Filed Aug. 9. 1943 8 Sheets-Sheet '7 l Vinili/TIERSINVENTOR. MEW/Pl G. BUS/GAMES H. G. BuslGNlEs 2,4

ANTENNA ARRAY Filed Aug. 9, 1943 8 Sheets-Sheet 8 IN VEN TOR. ,ww/W 6.axs/Gw/e's determined desired conditions Patented July 6,1

UNITE Nes t Telephone and t i N. 3., a corporation oi- Delaware oliiCorporation,

Application somt aises. serial no. coarse (ci. ses-115) 2@ Claims.

This invention relates to radio antennas and in particular to directiveantenna arrays and assoelated apparatus whereby the directivity of thearrays may be controlled in accordance with pre- I or requirements. 'Theobjects of my invention are:

To provide a single antenna array and associated apparatus capable oi?simultaneously re ceiving a plurality o1 radio transmissions either ofthe same or of different frequencies from diderent directions.

To provide a single antenna array and associated apparatus capable oisimultaneously receiving a plurality oi radio transmissions of dierentfrequencies from any one given direction.

To provide a circular antenna array and asso- -ciated control apparatusby which radio transmissions i'rom any direction in azimuth may bereceived.

To provide a circular antenna array and assoelated control apparatus bywhich the directivity of the array may be rotated in, the horizontalplane at substantially any rate.

To provide a completely .automatic direction finder capable ofdetermining the direction of a radio transmission in the horizontalplane.

To provide a voltage operated phase changer by which the phase of avoltage or current wave may be advanced or retarded through 360electrical degrees.`

To provide a voltage operated phase changer and control apparatustherefor by whichl the phase and magnitude ci a voltage or current wavemay be changed in accordance with a given cycle.

These and other objects and features will be come apparent from thefollowing description taken in connection with the attached drawingsillustrating several embodiments of my invention, and wherein A Fig. 1is a schematic circuit diagram showing an antenna array and associatedcircuits in accordance with one embodiment of my invention;

Fig. 2 is a schematic diagram illustrating a voltage operated phasechangerin accordance with my invention:

Fig. 3 is a diagram illustrating one ymethod for determining an antennaarray in accordance with my invention;

F154 is a vector diagram illustrating the magnitude and phase relationsof voltages which may be obtained from the phase changer shown in Fig.1'

Fig. 5 is a second embodiment of my 4invention wherein a plurality ofar'itennas'V are arranged in circular array;

Fig.y 6 represents the field pattern ofthe array resulting from a givenpredetermined set of conditions shown in Fis. 5

o I l Fig. 'I is a polar diagram used in explaining the principles of myinvention; i

Figs. 8 and 9. illustrate respectively the phase and magnitude relationsof currents delivered to the transmission lines shown in the antennaarray of Fig. 5;

Fig. i0 is a schematic diagram of e, phase control device forcontrolling the phase changer ci.'

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lil

Fig. 11 is a sectional diriga-...ilV of the phase control device asviewed from the section line ii--i i of Fig. 10.

Referring to Fig. l I have schematically iiius trated a six-elementlinear antenna array togather with receiving apparatus and contro!equipment suitable for receiving a, plurality of radio transmissionsfrom different directions as set forth in the first two objects of myinvention. In the figure, elements i-i represent six antennas arrangedin linear array. These antennas are preferably aperiodic and thereforeare capable ol substantially equal response over a wide irequency band.Connected across an. impedance in each antenna are two phase changingdevices shown as ,blocks Bland iii. Each block represents apparatus forchanging the magnitude and phase of the voltage induced in the antennacircuit. The specic circuits for the phase changing dee vices areillustrated in Fig. @ne set of phase changers, represented by .referencecharacters ior example, is for detemninin the elci pattern oi theantenna array for one particular frequency. The other set of phasechangers, it. are for deter-- mining the held pattern for another.frequency which may have a maximum dircctivity either in the same or ina dierent direction from that determined by the phase changers ii. It isto be understood that whereas I have illustrated only two groups ofphase changers, any number of groups may lbe employed each group actingentirely inde pendently from the others and determining a separate eldpattern. Extending from the -phase changers il are a plurality oftransmission lines I2. Each line extends from the phase changer to whichit is connected at one end to a receiver I4 which may be located at aremote point. The output impedance of the phase changer is matched tothe impedance of the line. In the interest of economy of transmissionlines it is preferable that adjacent lines, for example those associatedwith antennas i and 2, be connected together at a point Iiiv and thatthe combined energies from these lines be transmitted over a single linei8 to receiver it. The dimensions of the lines are preferably so chosenthat an impedance match occurs at the junction point i8. It ispreferable though not essential that the elecand all oi the In a similarmanner, transmistrical length of all of the lines i2 lines I8 be equal.

e cathode follower phase invertor type.

3 sion lines 20 extending from phase changera i0 are connected togetherat point 22 and the ener- `gies therein are transmitted over a commonline 20 to a. separate receiver 20.

Associated with receivers I and 26 are phase change control devices 20and 00 respectively.

, Control channels 3|30 extend from the phase control device 28 tothephase changers 0. In a. similar manner control channels 31-02 extend.from the phase control device 00 to the group of phase changers I0.Each control channel, 3iy for example, is to be considered asrepresenting a number of conductors sufilcient to control the loperation of a single lphase changer.

In general the phase changers, as illustrated by the schematic wiringdiagram of Fig. 2, comprise a plurality of vacuum tube amplifiers oi theI have illustrated each phase changer as comprising three ampliiiers A,B, and C. The input circuits of the amplifiers are connected in parallelacross an impedance 50 in the antenna circuit of each of the antennas|6. Between the point 5| and the control grids I52, 53 and 50 ofampllers A, B, and C respectively. there is a connection havingelectrical characteristics such that the voltthe point 5| to the grid 53there is an inductive reactive connection. Any voltage occurring on grid53 as a result of an applied voltage at point 5|, therefore undergoes alagging phase shift. Similarly, a capacitive reactance is connectedbetween the point 5i and the grid 00 whereby any voltage occurring onthe latter grid, as the result of a voltage applied to the point 5|,undergoes a leading phase shift. The inductive and capacitive reactiveconnections are represented by the inductor 56 and the capacitor 50.Shouti ing the inductor 56 is a variable resistance 00 by which thephase voltage and the grid 00 may be controlled over a predeterminedrange. Similarly, a variable resistance 62 is shunted across thecapacitor for varying the phase of the voltage and the grid 54. `It isto he understood that the reactors 50 and 50 may also be made variablefor producing phase variations of voltage on the grid to which they areconnected.

Between the cathode 60 of amplier A and ground, there is a resistor 60.The voltage oleveloped across this resistor is in phase with the voltageappearing across the resistor 50 in. the

' antenna circuit. A lead 68 connected to the junction point between thecathode 60 and the resistor 6B has a voltage impressed thereon having aphase relation the same as that across the resistor 65. Between'theanode ill of amplifier A and ground, there is a second resistor l2, andacross this resistor a voltage is developed having a 180 phase relationwith respect to the voltage impressed across the resistor 50 in theantenna circuit. A lead 14 connected to the Junc- ,tion point of theanode l0 with resistor 'i2 has the same phase as that developed acrossresistor 12. It will therefore be seen that the voltages developedacross conductors 00 and 10 have a 100 phase relation with respect toground. The magnitude of this voltage is controlled'in part by the valueof the voltage appearing on grid 10, and the source of this controllingvoltage is in the phhse control device 20. A conductor 'l0 extendsbetween the grid l0 and the phase control device 20, and is one of theconductors making up the channel 3| described in connection with Fig. 1.A'second conductor 80 extends between the anode 10 and the phase controldevice 20 and is for the purpose oi' impressing a positive potential onthe anode. A choke coil 02 prevents radio frequency currents fromflowing in the conductor 00. The conductor 00 represents another of theconductors constituting the plurality of conductors of channel 3|. Themagnitude of the voltage applied to theanode also controls the magnitudeof the voltage appearing across the conductors 00 and 14. The capacitorlay-passes the radio frequency current to ground and blocks directcurrent from the conductor 00 from ground.

Referring now to amplifier B, the resistor is connected between thecathode 92 and ground. The resistor 00 is connected between theV anode00 and ground. The phase relation between conductor 00 and ground andthe conductor-'|00 and ground is as will be seen from the description inconnection with amplifier A. The phase relation between the voltageappearing across the conductors 00 and 'le and the voltage appearingacross the conductors 00 and |00 will have a substantially 60 phaserelation as determined. by the reactor The magniturleoi the voltageacross conductors 00 and. i00 .is determined by the voltage appearing onthe grid lili: and the anode 06. The arid voltage is impressed from thephase control device 20 to the grid |02 over the line |00 whichconstitutes part of the channel 3|. I'he anode voltage is transmittedover` the line |06 extend .ing between the anode 00 and the phasecontrol device 20 and this line |06 likewise constitutes part of thechannel 0 I.

With respect to amplifier C, the phase relation hete/een the voltageacross conductor |00 and 'ground d the voltage across conductor |-|0 andground la 300. However, due to the reactor 00.

the voltage between conductors |00 and ||0 is4 displaced substantially60" from the phase of the voltage across conductors 00 and 10. 'Themagnitude of the voltage between conductors |08 and lill is determinedby the voltages applied to the grid iii?. and the anode lit of amplifierC. The voltages are impressed over lines Il and IIB respectively fromthe phase change control device 20. Lines im and H0 constituteconductors of the control channel 3l. It will be seen that in theillustrated case, the control channel 3| cofmprises six conductors i8,00, |00, |06, H6, and H0.

The output conductors 08 and 14 of amplifier A are connected to theoutput conductors 90 and |00 of amplifier B and to the output conductorsof |00 and @i0 of amplier C at the points. |120 and |22 in such a mannerthat the phase relation of the voltages appearing across points |20 and|22 due to the above mentioned conductors are apart. This phase relation'may be obtained by inverting the phase of the voltages acrossconductors 93 and |00 and across |08 and ||0 with respect to the pointsH20 and |22. Under these conditions, if the voltage appearing acrosseach of the resistors 50, i2, 00, 00, |20 and |30 were equal inmagnitude, the combined voltage across points |20 and |22 would be zero.However, if a. voltage appearing across any of the resistors inmediatelyabove mentioned was reduced or increased', the voltage across points |20and i22 would no longer be zero, but would have a iinite value and phaserelation dependent upon the magnitude of the voltages appearing acrossthe resistors. Connected across points i2lll and |22 are the lines l2 or20 of, Fig. 1 as the case may be.

Referring again to Fig. 1 it 'will be seen that due to the commonconnections at points Mil and M2 of the lines I8 of which the lines I2may be considered as branches, a change of voltage across any or theresistors in any of the amplifiers of the phase changers 8 will resultin a. change in magnitude and phase of the final voltage impressed uponthe receiver i4. Likewise when considering phase changers lll, a changein voltage appearing across any resistor therein will aiect themagnitude and phase ultimately impressed upon receii -r 26. However,there is no interaction between phase changers 8 and In and theredoreeach receiver will be controlled by the respective phase changers towhich it is connected.

In Fig. 3 I have shown the manner in which a single antenna. array maybe designed to receive vradio transmissions from two arbitrarydirections in such a manner that the iield patterns of the antenna arraywill be a maximum in the direction from which the transmissions arereceived. It two diierent frequencies are being received thedirectivities of each transmission may be the same and there will be nointeraction. If the radio transmissions are of the same frequency, inorder to prevent interaction of the receivers it will be necessary forthe transmissions to have different directions with respect to theantenna array. I have assumed two transmitters located at points S1 andSe and a receiver located-at-R. The angle .between the transmissionsfrom Si and Sz with respect to R is There are many types of arrays knownto the prior art and I have chosen the type known as a binomial arrayfor describing my invention. .at right angles to the direction oftransmissions from S1 a six-element binomial array is laid out. As iswell known the spacing between the antennas of the array are one-halfwavelength at the operating frequency which I have designated in Fig. 3as The relative lmagnitudes of the voltage outputs from the wavechangers associated with each antenna are 1-5-10-1051 sequentiallybetween end antennas of the array. It is of course understood that aone-half wavelength separation is equivalent to a 180 time phasedisplacement. Construction lines are drawn parallel to the transmissionsfrom S1 through the antennas of the array. A similar array isconstructed at right angles to the transmissions from S2 and thedistance between the antennas are designated Through the antennas of thesecond array, construction lines are drawn parallel to the transmissionsfrom Sz. At points where the two sets of construction lines intersect,the antenna array comprising antennas l-2--3- t--E-ti in accordance withmy invention may ,be positioned as shown in Fig. 3. It will be seen.that projections from the antennas to assenso points on a line at rightangles to either directie of transmission will be equal to one-half tbwavelength of either transmission.

' Considering transmissions from S1 for exampl it will be observed thatthere will be a difieren( in phase between the energies arriving at ttvarious antennas o the array, and that this phat relation for a givenwavelength is dependent upc the angle ebetween the array and thedirection l reception. This angle I have designated 0 an the phasebetween the energies induced in an two adjacent antennas is equal to 1rcot 0 radlan In order that the antenna array will have field patternwith a maximum directivity in tr direction of S1, it is required thatthe effectii outputs of wave changers associated with ti antennas becophasal. This result may be ai tained as follows:

A wave front passing through the array will ir tercept the antennaclosest to the transmitter certain number of electrical degrees in spalphase before intercepting the second antenn If the .iective outputvoltage from a pha: changer associated with the first antenna is dllayed an amount equal to this space phase, ti eiect upon a receiverwould be the same as the receiver were being acted upon by in-pha:voltages from both antennas. Applying th principle to all of theantennas of the array, will be seen that by a plurality of suitable pha:changing means, the eflective output voltagn from all antennas can bemade cophasal.

In Fig. l I have illustrated by a group of vel tors, certain conditionswhich must prevail i order that the antenna array ofFig. 3 have tldesired maximum directivity in direction S1 fro: the receiver R. Theangle 0 between the arr: and the direction of reception is assumed to lThe vector Ve represents the output voltar from the phase changerassociated with antenz 6. Vs represents in magnitude and phase tl valueof the output voltage from the wa changer associated with antenna 5. Thepha relation of the voltage induced in antenna 5 wii respect to thatinduced in antenna 5 is 104 represented by the angle between Vs and Vs.Th means that the phase changer associated wi antenna 5 must advance thephase of the inpi voltage by 104 in order that the outputs of tl twophase changers will be cophasal. A simili analysis applies to all of theremaining vecto V4, V3, V2 and V1. A detailed example of tl manner inwhich the phase changers operate provide an output of the desiredmagnitude ar phase will be given hereinafter in connection wi1 a secondembodiment of my invention.

Although I have described my invention 1 embodied in the diagram of Fig.3 as comprisii an antenna having a directivity in two directior it is tobe understood that any number of dire tivities could be obtainedprovided only that tl distance between adjacent antennas is substaitially equal to the operating wavelength divldr by twice the sine of theangle between the dire tion in which the antenna array extends ai thedirection of reception. This distance shown in Fig. 3 as The directivitycan therefore be varied over considerable angle without materiallyaiiectii the field pattern of the antenna array.

Referring to Fig. 5 I have illustrated anoth` embodiment of my inventionwherein a plurali -phase changer of the type illustrated in Fig. 2 andfrom each wave changer a transmission line extends to a centralreceiver. At any instant oi time a predetermined number of the antennasare conditioned through the medium of their associated phase changers sothat as a group they are responsive to radio transmissions from apredetermined direction -and substantially nonrespo'nsive totransmissions from other directions. Even though the antennas constitutea receiving array, the antenna may be said to have a eld pattern havinga maximum directivity in a predetermined direction.

In accordance with my invention the ileld pattern of the directive-array is rotated in azimuth. The rate of rotation may havesubstantially any value, being determined in accordance with myinvention by the rate of rotation of a mechanical phase control deviceto be hereinafter described. The rotation of the eld pattern isaccomplished by progressively energizing -antennas on one side of thegroup which is active at any given moment and cie-energizing antennas onthe other side of this group.

In order to describe my invention, it is convenient to discuss a givenantenna array which is conditioned to receive in accordance with apredetermined field pattern. For example in Fig. 5

-I have illustrated an outer antenna array in which fifteen equallyspaced antennas are positioned on the circumference of a circle having aradius of 432 electrical degrees and an inner antenn'a array positionedon the circumference of a circle having a radius of 340 electricaldegrees. One antenna of each array is positioned on a common radius.Adjacent antennas of the array are spaced 24 electrical degrees apart.Considering for the moment the outer array, the adj-acent antennasthereof are spaced apart one-half wavelength at the operating frequencyor 180 electrical degrees. It is from this given condition that theradius of the array equals 432 degrees.

In Fig. 5 I have not shown all of the antennas constituting the completearray, since so doing `would merely complicate the drawing and addnothing to a clear understanding of the operation of my invention. Ihave assigned reference characters Ai-Ae to `a group of antennas in theouter arrayand Aff-A12 to a group of antennas in the inner array. Adiscussion of the manner in which these antennas and their associatedwave changers are conditioned to operate will be suiiicient tocompletely describe the operation of the system as a whole. Oppositeeach antenna I have indicated certain voltage values and phase relationsto be used in describing its operation. As-

i suming the direction of maximum reception is rotating'in the directionof arrow Da the upper values indicate certain voltage and phaserelations when the antenna array is conditioned to receive from thedirection of the arrow D1 and the lower values indicate conditions whenthe array is conditioned to receive from the direction D2. The amplitudeand phase relations of the voltages d elivered from the phase changersof the array gradually shift from one set of values to the other as thedirectivity of the array changes from the direction of Di to Dz as willbe hereinafter more completely described. When the array is receivingfrom the direction Di, the phase changer associated with antenna As isdelivering a maximum voltage E having a phase relation of zero degreestaken as a reference. Phase changers associated it with antennas A2 andA4 on either side of A: are conditioned to deliver a voltage of .67Ehaving a phase relation of 37.2. Similarly, phase changers associatedwith antennas A1 and A5 are conditioned to deliver a voltage of .167Ehaving a phase relation of 143. It will be observed that the values.167-.67-1-.67-.16'7 bear the relation of 1-4-6-4-1 respectively, andthat these values represent magnitudes corresponding to the effectivereceived voltages in a binomial array of live antennas. As abovedescribed in 'connection with Fig. 3, in order that an antenna arrayhave a maximum directivity in a direction normal to the array, it isnecessary that the effective voltages f delivered from the antennas havea cophasal re- Since the antennas of my array are on lation. the arc ofa circle, it is necessary that means be provided in the form of a phasechanger to develop these cophasal voltages. For example, in order thatantenna Az deliver a voltage in phase with antenna A3, the phase changerassociated with A2 must advance the phase of the voltage wave as itstrikes the antenna by 37.2. Similarly, the phase changer associatedwith antenna A1 mustadvance the phase of the voltage wave interceptingthe antenna by 143.

As is known in the prior art. in order that an antenna array have aunidirectional receiving pattern with a maximum directivity normal tothe array, it is customary to provide either a second array ofreflecting antennas usually spaced onequarter wavelength from theenergized antennas' or to provide means for energizing this secondarray. .Due to the fact that the antennas of my invention are aperiodic,it is necessary to provide a second energized array rather than one ofthe unenergized or reflector type. Accordingly, a second group ofantennas Ar-Aiz is provided to form an inner array.- Since the antennasof the arrays are on the arcs of circles, it is impossible to locate allantennas of the inner array so that they will be one-quarter wavelengthfrom corresponding antennas in the outer array. However, the antennas ofthe inner array may be conditioned to deliver a voltage wave having aphase relation such that substantially the same efl'ect is obtained asif the one-quarter wave phase relation existed.

The values of the voltages and phase relations delivered by the outputof antennas Arf-A12 is recorded in Fig. 5.

The above discussion has dealt with the magnitudesl and phase relationsof voltages delivered by the antennas under consideration when max-limum reception is from the direction D1. If now the various magnitudesand phase relations of all the antennas be changed in a manner such thatthey correspond to the lower sets of figures shown adjacent the variousantennas, the antenna array as a whole Will have a field pattern suchthat its maximum directivity is in the direction D2. An examination ofthe drawing will show that under these conditions antennas A: and A4 forexample will deliver equal voltages of .89E having a phase relation of9.5. The antennas of a binomial arrayunder these conditions wouldnormally have sequential voltage values of 1-5-10-10-.5-1. However,since the outer antennas of a six-element array deliver only nl; of thetotal voltage developed by the array and the power varies with thesquare of the voltage, these outer antennas have been disregarded in thecomputation. By so doing no 'serious error could be noted in anypractical system. For this reason the magnitudes of voltages deliveredby antennas A1, As, A1, and A12, have been considered as zero. The

phase relation however of these voltages has been recorded to indicatethe phase relation at which voltages would begin to be developed bythese antennas during the rotation of the field pattern. The fieldpattern for the condition in which antennas .A2-A5 of the outer arrayand antennas Aia-A11 of the inner array are conditioned for receptioniorthe direction De has been computed and is shown on the polar diagram ofFig. 6. It will be seen from this diagram that the field pattern has avery marked directivity in the direction Da.

Y I will now describe the manner in which the phase changers areoperated so as to deliver output voltages having a desired magnitude andphase in accordance with the conditions indicated on-Fig. 5. In Fig. 7are plotted two curves M and N from the voltage and phase valuesappearing on Fig. 5. Curve M shows the order of change of the voltageand phase delivered by a phase changer associated with any antenna inthe outer array. Curve N shows similar values for a phasechanger'associated with any antenna of the inner array. These curves aresubstantially two spirals having a 90 phase relation therebetween: Adiscussion of the variation in magnitude and phase of voltages from-antennas in the outer array only willbe given in order to not undulylengthen the specification and since a similar discussion would apply toantennas of the inner array.

In Fig. 7 I have shown a plurality of vectors extending from the originto certain points on curve M, these vectors representing the specificvalues of magnitude and phase of voltages appearing on Fig. 5. Curve Mis interpreted as follows Whenthe directivity of the array changes fromD1 to Dz, the magnitude and phase relation of the output voltage fromantenna n as represented by vector V7 changes to a value represented byvector V8. At the same time the magnitude and phase relation of outputvoltages from antenna Az changes from a value represented by vector Vcto a value represented by vector V10, and likewise the output fromantenna A1 changes from vector V11 to zero. It will be observed thatduring this period there is considerable reduction in magnitude and anincrease in phase diderence in the voltage outputs from antennas A3, A2,and A1. On the other hand, the output from antenna A4 'increasesro-rn avalue represented by vectorVo to a value represented by" vector Va,while the output from vantenna As increases from the value representedby vector V11 to the value represented -by vector V10. It is clear thatthe changes in output just described occur While the drectivity ischanging from the direction D1 to the direction D2 or through` 12. Themanner in which the magnitude and phase of the output voltage from anyantenna changes through one complete rotation of the eld pattern isshown on Figs. 8 and 9 respectively for that portion of the completecycle cluring which any given antenna is conditioned to receive. In Fig.8 curve 20d shows a variation in phase through which the output of anyantenna of the outer array passes during 'a 120 rotation of the heldpattern. Curve 2li-2 shows the change in phase through which the voltageoutput from any antenna oi the inner array passes during the sameperiod.

The phase changer which is associated With any of the antennas of thearrays, is shown in Fig.l 2 and has been previously described. Themanner in which the output of the phase changer is controlled so that itwill deliver a variable voltage having a variable phase in accordancewith the reduirements of any antenna `shown in Fig. 5 will now bedescribed. First, from the wave changer associated with each antenna ofthe outer antenna array, there extends a -transmission line 220 to acentral receiver. Preferably these transmission lines are of equallength and have the same electrical characteristics. Other similartransmission lines 222 ex tend between the phase changers associatedwith the various antennas of the inner array and the central receiver.These latter transmission lines should also be of equal length andelectrical characteristic, but need not necessarily be equal to thefirst group oi transrnissifm.l lines 220. Each transmission line hasbeen diagrammatically illustrated in Fig. 5 as a single conductor. Inreality the line is preferably composed oi two conductors extending fromthe points 12D and E22 in Fig. 2.

In Fig. 5, as well as Fig. l, I have illustrated each phase changer unitas being connected directly with its associated antenna., and have alsoillustrated a transmission line extended from the phase changer to thereceiver. It is to be clearly understood that each antenna could befirst coupled to a transmission line with the far end of the lineconnected with a phase changer unit. Under these conditions all thephase changers could be centrally located at the receiver. If this typeofconstruction were employed it would of course, be desirable to matchthe output impedance of the antenna with the input impedance of thetransmission line and the output impedance of the transmission line withthe input impedance of the phase changer in accordance with knownmethods.

Also extending between each phase changer and a phase control device isa control channel. Each channel. is diagrammatieally illustrated in Fig.5 as a line 230. Each line` is actually coin posed of a plurality ofconductors and as shown in Fig'. 2 these conductors are identified byreference numerals lil, Sil, itil, iilii, lili, iiil. The phase controldevice 232 is preferably located adjacent the central receiver but inFig. 5 it has been drawn at the top of the iigure in order to maire thediagram less confusing. lt is the function of the phase control deviceto apply voltages to the various grids Mit, and lil of the ainpliersshown 2 or" such magnitude that the output voltage from the combinedamplifiers as it e nears across ternurnals i2@ and iti: will have t-..desired amplitude and phase. ,es an example when the output from antennaAs has an amplitude ci E and phase zero, iet it be required to producean output voltage from A2 of a magnitude .67E vand phase of 37.2.

Considering Figs. 2 and 7 the output of ampliiier A varies in accordancewith a vector en tending from the origin horizontally to the right alonga line This line represents the refer-A ence from which all phases aremeasured. The line 2&2 positioned in the 2nd quadrant of the diagram ofFig. l is that along which the vol-- tage output from amplier E varies.This line bears an angular relation with respect to line 2d@ ofapproximately 127 in accordance with this example and for a reason whichwill be brought out later. This angle of 127 is determined by thereactor 5e in the grid circuit of amplifier B and the polarity in whichthe output leads 96 and |00 are connected to points i2@ and |22. 1n

antenna arrays.

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the third quadrant n line 2M extends in n, direction havingr an angularrelation with line 21m of 216 for reasons which will be described later.It is along this line that the vector of the voltage output fromamplifier C extends. The direction oi' line 2M is determined by thecapacitor 5a and the polarity in which the output leads Iil and liu areconnected to points 12u and i22.

-Digressing for the moment from the particular problem at hand, it willbe noted that if the volt'- ages applied to the grids |02 and I i2 ofampli- -iiers B' and C respectively were such that a current output fromthese amplifiers were reduced to zero. the vector output from thecomplete phase changer would be determined solely by the output fromamplifier A. The vectors normally extending along the lines 2M and 2Mwould be reduced to zero, and the output vector from amplifier A wouldlie on line 240. The magnitude of this vector could be determined by thevoltage applied to the grid 18 and to the anode l0. As a matter of factthe output vector from antenna A1 extends along this line. and may berepresented by the vector V7. At the same instant of `time it is desiredthat the output from antenna A: have a magnitude of .67E and a phaserelation o1' 37.2, as shown by vector V2. This vector may be obtained byreducing the voltage on the grid 18 of amplifier A to a value where theoutput is represented by vector V12 while at the same time increasingthe voltage applied to the grid |02 of amplifier B until the output fromthis ain-v pller may be represented by the vector V13. The output fromamplifier C is maintained zero during this time. The sum of vectors V12and V13 is equal to the desired vector Vo.

At this same instant the output voltage from antenna A1 should have avalue of .167E and a phase relation of 143. This voltage is shown byvector V11 and may be obtained by reducing the output from amplifier Ato zero, and maintaining outputs from amplifiers B and C equal to valuesshown by vectors V14 and V15 respectively. In s. similar manner thedesired amplitude and phase relation of any voltage of any antenna ofthe array may be obtained.-

The manner in which the direct current voltages to be impressed on thegrids 16, m2, H2, and amplifiers A, B and C respectively may begenerated is illustrated in Figs, 1() and 11. In these figures I haverepresented a plurality of variable capacitors. Each capacitor comprisestwo electrodes, one fixed and one rotatable. One of these variablecapacitors is provided 'for each phase control grid electrodecontrolling the output of an ampliiier in all phase changers. In thepresent illustration there would thus be a total oi' 90 capacitors,three for each phase changer of which there is one for each of thethirty antennas comprising the inner and outer However, I haveillustrated in Figs. and 11 only forty-five of these variable capacitorsor a number sufiicient to control the outputs of the antennasconstituting one of the circular arrays. It is understood that the otherforty-five variable capacitors for the other array would be similar tothose illustrated in Figs. l0 and 11. As illustrated by these figuresthe fortyfive fixed electrodes of the variable capacitors are dividedinto groups of 15, each group lying on the periphery of-a circle. I havedesignated these groups as X, Y and Z. Associated with groups X, Y and Zare three rotating electrodes X', Y and Z' respectively. The rotatingelectrodes may be likened to cams having predetermined irregular pliierC of the phase changers. served that the fixed electrodes of group X areiig incre-fi as shown in iilg. 10. As the electrodes X', Y' and E'rotate, it will be seen that the interelectrode capacitance between thesurfaces oi the rotating electrodes and the fixed electrodes changes dueto the irregular shape of the former.

The fixed electrodes Xi-Xn are connected to the phase control grids 16oi.' the amplifiers A associated with the phase changers in the outerantenna array. Similarly, each xed electrode Yifir. of group Y isassociated with the phase control grid m2 of' amplier B of these phasechangers and fixed electrodes Zi-Zin of group Z are connected to phasecontrol grids |12 oi am- It will be obco'nnected to that amplifier Awhose output is in phase with its input, that the electrodes of group Yare connected to that amplifier having an inductive reactance in itsinput circuit, and that the electrodes of group Z are connected to thatamplifier having a capacitive reactance in its input circuit.

In the lead between each fixed electrode in groups X, Y, Z and a phasecontrol grid in the phase changer, there is a vacuum tube rectifier D.shown in Figs. 10 and 11 these rectiers may consist of atriocle in whichcase an amplifying as well as a detecting action is obtained. It is tobe understood that any equivalent rectifying device such as a diode or aselenium rectifier may be employed.

A source of high frequency current 250 is connected between the rotatingelectrodes X', Y' Z and ground through the medium oi. a brush 252bearing on a ring 251i the latter being a part of or electricallyconnected to the rotating electrodes. The circuit 256, tuned to thefrequency ci.' the source and comprising a capacitor 258 and inductor'260, acts as a tank circuit connected across the output of the highfrequency source to improve the regulation thereof. The frequency of thesource 250 should be high enough to make the capacitance reactancebetween the rotating electrodes and any fixed electrode relatively low.SuiHcient energy may thereby the transferred to the rectiiiers to causethem to operate eiilciently. The rectified output of the rectifiers ispassed over the control circuits, 18, |04 and |18 for exampie. andimpressed on the phase control grids of the phase changer amplifiers.Referring again to Fig. i it will be observed that the vector Vv andtherefore the output of amplier A has a magnitude for a portion of theoperative cycle at least, greater than the outputs of either amplifiersB or C at any time. This means that the capaci'- tance between therotating electrode associated therewith X and any fixed electrodeX1-X15, must be proportionately greater than the capacitance betweeneither of the other rotating electrodes and their corresponding fixedelectrodes. This is illustrated in Fig. 10 wherein Athe rotatingelectrode X has a relatively long electrode surface opposite the fixedelectrodes. Referring to Fia. 7 it was mentioned that the line 242 waspositioned at an angle of approximately 127 from the line 2da. This line'M2 was drawn parallel to the tangent of curve M at the point As'. Bysuch a construction it is seen that the vector V1 undei-goes no abruptchange in magnitude as it rotates from point Aa. This in turnimeans thatthe periphery of rotating electrode X' has the form oi a smooth curveand facilitates its design. For similar reasons the line 244 of Fig. 'Ioccupies the position of 216 with respect toline 260, and the electrodeZ' may have a smooth outer periphery.

With the electrode X' in the position as shown in Figs. and 11, it willbe seen that the reactance between it and electrodes X3 is a minimum,whereas the reactance between electrodes Y', Z', and Ya Z3 respectivelyis a maximum. This means that only amplier A-of the phase changerassociated with electrodes Xs. Ya, and Za is delivering an appreciableoutput voltage. The high reactance between electrodes Y', Z and Ya Z3respectively prevents energy iiow from the source 250 across theseelectrodes with the resultfthat the phase control grids of ampliers Band C of the phase changer are biased to cutoff.

However during this period, the reactance between Y' and the two fixedelectrodes Ys and Y4 is a minimum, maximum energy is being passedbetween these electrodes, andthe result is that the phase of the outputci adjacent antennas is controlled primarily thereby. It must be kept inmind, however, that the voltage output and phase from any antenna is, ingeneral, controlled by the joint action of all energies passing betweenthe rotating electrodes and any group of fixed electrodes X2, Y2, and Z2for example. As the electrodes X', Y', and Z' rotate, they come intooperating relation with other groups of fixed electrodes than thoseshown in Fig. 10 and in this manner the eld pattern of the antenna arrayis rotated.

The-manner in which the output from the receiver may be employed toindicate the direction from which a signal is being transmitted will nowbe explained. The receiver itself may be of any usual type, for examplea superheterodyne employing the usual tuned circuits for selecting thefrequency to be received. The output from the receiver is connected tothe rotating coils 210, 212 of a cathode ray indicator 214 asillustrated in' Fig, 11. The coils of the oscillograph are driven insynchronism with the rotating electrodes of the phase control device.This is illustrated in Fig. 11 by the lines 216, and 213 connecting themotor 280 to the shaft 282 of the phase control device and to theindicator 2li.

Normally, when no signal is being received, a lluorescent spot willappear at the center of the oscillograph screen, the position of thisspot being controlled by known means. When a signal is being received,current from the receiver passes through the coils 210 and 272 causingthe spot to trace on the screen a pattern corresponding substantially tothe field pattern of the antenna as shown by the curve 204. From theposition of the trace with respect to a scale (not shown) on theindicator, the direction from whichrthe received energy is beingtransmitted can be observed.

In describing my invention I have chosen specie examples of antennaarrays comprising a given number of antennas. The dimensions of thearrays were also assumed. It is to be clearly understood that thesevalues were assumed for the purpose of illustration and description onlysince other arrays having a'greater or a lesser number of antennas couldequally well have been described. In describing the phase changer andphase change control device it has been assumed that the various valuesof voltage output were controlled by applying suitable voltages to thephase control grids of the ampliers. .These output voltages could alsohave been controlled in part by applying suitable voltages to the anodeslill of the amplifiers as taught in my copendlng application SerialNumber 481,760 rlled April 3, 1943 which issued January 27, 1948 asPatent No. 2,434,904. Likewise in place oi' balanced transmission linesextending between the phase changers and the receivers I could haveemployed unbalanced lines such as the concentric conductor linesdisclosed in the abovemamed copending application. The above descriptionwas made by way of example only, and is not to be considered as alimitation on the scope ci my invention as set forthvin the objectsthereof and the accomg panying claims.

I claim:

1. A radio receiving system having a directivity variable in azimuth,comprising a plurality of antennas arranged in a predetermined array, areceiver, coupling means connected between said antennas and saidreceiver, said coupling means comprising a like plurality ci phasechangers and a plurality ci transmission iines, each an tenna beingcoupled to said receiver through one of said phase changers and throughsaid transmission lines, each of said phase changers being controllablyadapted to deliver voltages of a selected magnitude and phase, and a.control device connected to said phase changers applying a varyingcontrol to said phase changers so that said phase changers delivervoltages of varying magnitude and phase to said receiver.

2. A radio receiving system in accordance with claim 1 wherein saidplurality or" rinteimas are aperiodic and are arranged in e,

3. A radio receiving system accordance with claim l wherein said pluraci antennas are aperloclic and are arranged circular array.

A radio .receiving system scorda-nce with claim 1 wherein each of saidphase changers coma prises a plural-ity of vacuum tube ampliiiers, eachamplifier having an input and an output circuit, the phase relationbetween the voltages of the input and the output circuits oi oneamplifier being different irom the phase relation between the voltagesof the input and output circuits of another of said amplifiers.

5. A radio receiving system according to claim l wherein each of saidphase changers comprises a plurality of vacuum tube amplifiers. eachamplilei comprising an input and an, output circuit and a control grid.said control grid being con nected to said input circuit, connectionmeans for supplying voltage from one oir' said antennas to each of saidinput circuits, the input circuit of one of said ampliiers having areactance differont from the reactance of the input circuit of anotheroi said amplifiers, the maximum phase dii-ference between a voltagedeveloped on one of said grids and a voltage developed on another ofsaid grids being less i530, and circuit connections between the outputci"cuits of said ampliiiers to provide output voltages having a minimumphase diierencc greater than 6. A phase changer for changing themagnitude of a voltage and simultaneously changing the phase of saidvoltage through any angle between 0 and 360 comprising plurality ofvacuum tube ampliers each amplifier comprising an input and an outputcircuit, an input control grid and a phase control grid, reactive meansconnecting the input control grids of said ampliers to said inputcircuit to provide from a given input voltage a plurality of voltageshaving a maximum phase difference of less than at said input controlgrids, circuit connections inl said output circuits to provide voltagesdeveloped amasar! in said output circuits have a maximum phasedifference greater than 180 and control means connected with said phasecontrol grid for'applying a variable voltage to said phase control grid.

'7. A radio direction .iinding system having a predetermined directivitycontinuously variable in azimuth, comprising a plurality of antennas ina circular array, a receiver, coupling means connected between saidantennas and said receiver, said coupling means comprising a likeplurality of phase changers and a plurality of transmission lines, eachantenna being coupled to said receiver through one of said phasechangers and through said transmission lines, each of said phasechangers being controllably adapted to deliver voltages of a selectedmagnitude and phase, and a control device connected to said phasechangers applying a varying control to said phase changers so that saidphase changers deliver voltages of varying magnitude and phase to saidreceiver.

8. A radio direction finding system having a predetermined directivitycontinuously variable in azimuth comprising a first plurality of aperi-Iodic antennas arranged in circular array, a second plurality ofaperiodic antennas arranged in a circular array concentric with said rstnamed array, the separation of adjacent antennas in said first arraybeing substantially one-half wavelength, the radial distance between thetwo arrays being substantially one-quarter wavelength, a receiver,coupling means comprising a separate phase changer and a transmissionline coupling each antenna of both arrays to said receiver, a phasechange control device connected to each phase changer whereby inaccordance with predetermined voltage characteristics of said controldevice the phase changers deliver waves of predetermined magnitude andphase to said receiver in accordance with said directivity and meansconnected to the output of said receiver for indicating saiddirectivity.

9. A radio direction finding system in accordance with claim 8 whereinsaid phase control device delivers a control voltage to less than halfof the number of phase changers included in said coupling means at anyinstant of time. 10. A radio direction finding system in accord ancewith claim 8 wherein each of said phase changers comprises a pluralityof vacuum tube ampliers the outputs of said ampliers being connected toa single transmission line and connection means from said outputcircuits to said line whereby the output of each of said phase changersis the vector sum of the voltage outputs of said amplifiers.

11. A radio receiving system comprising a plurality of aperiodicantennas in linear array, a plurality of receivers, a first couplingmeans comprising a plurality Aof phase changers, a separate phasechanger coupling each of said antennas to one of said receivers, asecond coupling means comprising a second plurality of phase changers, aseparate phase changer of said second plurality of phase changerscoupling each of said antennas to another of said receivers, each phasechanger comprising a plurality of vacuum tube amplifiers, each amplifiercomprising an input and an outm put circuit, the phase relation betweenthe voltm ages of the input and the output circuits of one amplier beingdiierent than the phase relation between the voltages of the input andoutputs of another ampliiier.

12. A radio receiving system in accordance with claim 11 wherein thephase relations between the voltages of the input and output circuits ofall amplifiers included in said first coupling means `are such that theantenna array has a directivity in a first direction and wherein thephase rela-- tions between the voltages of the input and output circuitsof all amplifiers included in said second coupling means are such thatthe antenna array has a directivity in a second direction.

13. A radio direction finding system having a predetermined directlvitycontinuously variable in azimuth comprising a first plurality ofaperiodic antennas arranged in circular array, a like plurality ofaperiodic antennas, arranged in a second circular array concentric withsaid iirst named array, a plurality of phase changers, one phase changerbeing connected to each antenna of each of said arrays, phase controlmeans connected to said phase changers cyclically conditioning eachphase changer to generate from voltage applied thereto by the antenna towhich it is connected an output voltage having a predetermined variableamplitude and variable phase, connecting means to combine the outputvoltages from said phase changers, a receiver, means for connecting saidcombined voltages to said receiver, and an indicator connected to saidreceiver for indicating said directivity.

lefIn the method of determining the directivity of a radio transmissionfrom energy received by a plurality of antennasl arranged in outer andinner circular arrays and in which the output from each of said antennascontrols the `of all phase changers associated with the antennas of saidouter array to produce'a plurality of voltages varying in apredetermined magnitude and phase, simultaneously cyclically varying thebiases on the grids of the amplifiers of all phase changers associatedwith the antennas of said inner array to produce a second plurality ofvoltages varying in a predetermined magnitude and phase, combining allproduced voltages, and determining said directivlty from said combinedvoltages.

15. The method of determining the directivity of a radio transmissionfrom energy received by a plurality of antennas arranged in outer andinner concentric circular arrays comprising cyclically conditioningoverlapping groups of milacent antennas in said outer array to generatea plurality of voltages varying in magnitude and phase, simultaneouslycyclically conditioning overlapping groups of adjacent antennas in saidinner array to generate s. second plurality of voltages varying inmagnitude and phase, generating said plurallties of voltages inaccordance with said received. energy and said conditioning, combiningall generated voltages, and indicating the directivity ci saidtransmission from said combined voltages.

16. [i radio receiving system having a variable directivity comprising aplurality of antennas arranged in a predetermined array, a receiver,coupling means connected between said antennas and said receiver, saidcoupling means comprising plurality of phase changers and a plurality oftransmission lines, each antenna being coupled to said receiver throughone of said phase changers and through said transmission lines, each ofsaid phase changers adapted to deliver voltages of a selectablemagnitude and phase in accordance with the magnitude of the controlvoltages supplied to said phase changers and a 17 control device forsupplying variable voltages to said phase changers, said control devicebeing connected to said phase changers so that said phase changersdeliver voltages of varying magnitude and phase to said receiver.

17. In the method of controlling the directivity of reception of radiotransmisison from a plurality of antennas arranged in an array, thesteps comprising generating voltages of predetermined magnitude andphase, conditioning the energy received from each of said antennas inaccordance with said voltages, and cyclically varying said voltages bothin magnitude and phase over a range corresponding to the directivityrange.

18. In a method of controlling the directivity of reception of radiotransmission from a plurality of antennas arranged in an array, thesteps comprising generating voltages of different magnitude and phase,conditioning the energy received from each of said antennas inaccordance with a separate one of said voltages, and cyclically varyingsaid voltages both in magnitude and phase over a range corresponding tothe directivity range.

19. In a method oi controlling the directivity of reception of radiotransmission from a plurality of antennas arranged in an array, thesteps comprising generating voltages of diierent magnitude and phase.conditioning the energy received from each of said antennas inaccordance with a separate one of said voltages, and cyclically andsimultaneously varying said voltages both in magnitude and phase.

20. In a method of controlling the directivity ci reception of radiotransmission from a plurality of antennas arranged in an array, thesteps comprising generating voltages of different magnitude and phase,conditioning the energy received from each of said antennas inaccordance with a separate one of said voltages, and simultaneously andcontinuously varying said voltages both in magnitude and phase.

HENRI G. BUSIGNIES.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,667,792 Martin May l, 19281,738,522 Campbell Dec. 10, 1929 1,922,115 Stone Aug. 15, 1933 1,954,898Stone Apr. 17, 1934 2,041,600 Friis May 19, 1936 2,140,130 Earp Dec. 13,1938 2,245,660 Feldman et al June 17, 1941

